1. Field of the invention
The present invention relates to an image forming apparatus, and more particularly, to an image forming apparatus having a plurality of functions.
2. Description of Background Art
An image forming apparatus is typically equipped with various functions, such as a scan function and a copy function. As for forming an image with the copy function, a user first turns a main power source on to activate the image forming apparatus. Upon completion of the activation of the image forming apparatus, a start key on an operation unit for mainly providing requests as to image formation is pressed down to start forming the image.
Generally, the completion of the activation of the image forming apparatus depends on the warm-up time of a fixing device provided in the image forming apparatus. In other words, the user has to wait until the fixing device reaches a predetermined fixable temperature after the main power source is turned on.
A technique to cut the time required for the fixing device to reach the predetermined fixable temperature after turning the main power source on for the purpose of reducing the activation time of the image forming apparatus is disclosed in Japanese unexamined patent publication No. 2005-70628.
Powering the main power source of the image forming apparatus activates respective units, including an operation unit for mainly requesting image formation, an image reading unit for reading originals and an image forming unit including the fixing device. The full activation of every unit brings the image forming apparatus into a usable state. Some current image forming apparatuses that need to load multiple functions and to display the functions on their operation units take a longer time required to complete the activation of the operation unit.
On the other hand, as for forming an image with a print function, for example, a user makes a request for forming an image from a personal computer, which is connected to the image forming apparatus, through a network without using the operation unit. Even in this case, however, in which the image formation request is issued from an external device of the image forming apparatus, the image cannot be formed until the activation of all units, including the operation unit, of the image forming apparatus is completed. As this goes to publication No. 2005-70628, even if the activation time of the fixing device is reduced, the user cannot get images until the activation of all other units is completed.